Cryogenic fluid supply system

ABSTRACT

Oxygen breathing gas is discharged from a system including a larger liquid oxygen supply container and a separate smaller storage-dispenser container which is inverted for filling by the supply container and then turned to the top-up position for dispensing.

United States Patent 1191 11] 3,797,262 Eigenbrod Mar. 19, 1974 CRYOGENIC FLUID SUPPLY SYSTEM 3.392.537 7/1968 woe rner 62/50 [75] Inventor Lester K. Eigenbrod, Indianapolis, 3'282'305 1 W966 Amolak [73] Assignee: Union Carbide Corporation, New Primary Examiner-Meyer Perlin York, NY. Assistant Examiner-Ronald C. Capossela Filed: Dec. 1972 Attorney, Agent, or F1rm--John C. LeFever 21 Appl. No.: 311,091

52 us. c1 62/50, 62/52, 62/55, [57] ABSTRACT 141/5, 222/3 [51] Int. Cl. Fl7c 7/02 Oxygen breathing gas is discharged from a system in- [58] Field of Search, 62/50, 51, 52, 55; 222/3; cluding a larger liquid oxygen supply container and a 141/5 separate smaller storage-dispenser container which is inverted for filling by the supply container and then [56] References Cited turned to the top-up position for dispensing. UNITED STATESPATENTS I V 2.951.348 9/1960 Loveday et a]. 62/50 9 Claims, 5 Drawing Figures PATENTEBm 19 m 3791.252 sum 1 0r 3 Pmmmums m4 3797262 sum 2 OF 3 FIG. 4

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CRYOGENIC FLUID SUPPLY SYSTEM BACKGROUND OF THE INVENTION This invention relates to a method of and apparatus for supplying gas, e.g. breathing oxygen, from a source of cryogenic liquid.

In the prior art systems for supplying breathing oxygen from a liquidoxygen source as for example described in U. S. Pat. No. 3,199,303, certain disadvantages have become apparent as the system is used in the home or hospital for medical therapy of pulmonary and cardiac disorders.

For example, it has been impossible to completely fill the inverted liquid oxygen storage-dispensing container from the larger liquid oxygen container positioned beneath and connected to the firstmentioned smaller vessel. This is because the gas vent conduit in the smaller container is relied on for both of the inverted liquid filling step and the top-up liquid dispensing step. Stated otherwise, the gas vent conduit terminates at about the mid-point of the smaller container so that it may be used for venting oxygen vapor when the container is in the bottom-up position for filling. Accordingly, the container may only be half-filled or the gas vent conduit would be submerged. This of course means that the liquid storage volumeis only half-used, an important disadvantage when one recognizes that the cryogenic liquid strage-dispensing container must be sufficiently small for manual handling by one person, in particular repositioning between top-up and bottom-up.

Another disadvantage of the prior art oxygen therapy system is that electricity is required to activate the fluid control system, and a power source is not always accessible to the user. Moreover the system was inoperable during power failures.

An object of this invention is to provide an improved cryogenic fluid supply system including a larger liquid supply container and a separate smaller invertible storage-dispensing container, wherein the latter may be completely filled with cryogenic liquid from the lower and larger supply container.

Another object is to provide such a cryogenic fluid supply system which may be operated to supply gas without electric power.

Other objects and advantages will be apparent from the ensuing disclosure and appended claims.

. SUMMARY This invention relates to a method of and apparatus for supplying gas from stored cryogenic liquid.

In a broad method aspect of this invention, gas is supplied from a system including cryogenic liquid supply container and a storage-dispensing container by the steps of: (a) providing a thermally insulated cryogenic liquid supply container; (b) providing a thermally insulated cryogenic liquid. storage-dispensing container ued and cryogenic vapor is discharged from the highest zone of inverted container (b) through the normally top end thereof for warming by and venting to the atmosphere. The temperature of the cryogenic fluid discharged from inverted container (b) is sensed during the cryogenic liquid charging and vapor discharging, and they are terminated in response to sensing of liquid. Containers (a) and (b) are then disconnected and cryogenic liquid-fill container (b) is turned to its top-up position. To supply gas, cryogenic liquid is upwardly flowed by overhead vapor pressure from the lowest zone of container (b) and discharged from the container top end. The so-discharged liquid is vaporized by atmospheric heat to form a gas supply and the liquid discharging and vaporization are continued until container (b) is depleted of liquid. The aforedescribed steps beginning with the container (b) inverting are thereafter repeated.

In a preferred method embodiment of the invention, a thermally insulated cryogenic liquid supply container (a) is provided having top and bottom ends, vertically aligned liquid discharge rigid conduit means, with a first end terminating'in thebottom end of the supply container and with a second end outside and above of container top end. First coupling means are joined to and axially aligned above the liquid discharge conduit second end. A thermally insulated cryogenic liquid storage-dispensing container (b) is also provided with top and bottom ends and is invertible between top-up and bottom-up positions. This container has vertically aligned gas vent-liquid fill rigid conduit means with a first end terminating in the top end of the container, and second coupling means are joined to the second end of the conduit means outside and above the container. The first and second coupling means are arranged and constructed for axial alignment and rigid vertical joining. Liquid withdrawal-gas vent conduit means have a first end terminating in the bottom end of container (b) and a second end outside and above the top end of the container.

An invertible liquid vaporizing-gas vent control circuit (c) is provided comprising liquid sensing means joined to the liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joining at one end to the liquid sensing means, atmospheric gas vent valve means joining the vaporizer other end, and signal transmitting means for automatically closing the atmospheric gas vent valve means in response to the sensing of liquid by the liquid sensing means, and user gas supply valve means between the atmospheric vaporizer otherend and the vent valve means.

Container (b) and liquid vaporizing-gas vent control circuit (a) are inverted and the container is positioned in vertical alignment with and above container (a), and the first and second coupling means are joined. Container (b) is charged with cryogenic liquid from container (a) by opening the atmospheric gas vent valve means for flowing cryogenic liquid upwardly from the lowest zone of container (a) by overhead vapor pressure therein through the liquid discharge rigid conduit means and the gas vent-liquid fill conduit means to the lowest zone of container (b). This cryogenic liquid charging is continued, and vapor is discharged from the highest zone of inverted container (b) for sequential flow through the liquid withdrawal-gas vent conduit means, the cryogenic fluid sensing means, the atmospheric vaporizer and the atmospheric gas vent valve means. The cryogenic fluid condition is sensed during the liquid charging and vapor discharging, and when cryogenic liquid is sensed this flow is terminated by closing the atmospheric gas vent valve means.

The first and second coupling means are then disconnected and container (b) and the liquid vaporizer-gas vent control circuit are turned to their normally top-up gas supply position. The gas valve supply means is opened and gas is discharged thereto. This gas is derived from cryogenic liquid flowing upwardly by overhead vapor pressure from the lowest zone of container (b), through the liquid withdrawal-gas vent conduit means, and vaporized in the atmospheric vaporizer. The liquid discharging and vaporizing are continued until container (b) is depleted of liquid and the aforedescribed steps beginning with the container (b) and liquid vaporizer-gas vent control circuit inverting, are repeated.

In the apparatus aspect of the invention, the cryogenic liquid storage-gas supply system comprises a thermally insulated cryogenic liquid supply container (a) having top and bottom ends, liquid discharge rigid conduit means being vertically aligned with a first end terminating in the bottom end of the supply container and a second end outside and above the top end of the container. First coupling means are joined to and axially aligned above the liquid discharge conduit second end. A thermally insulated cryogenic liquid storagedispensing container (b) is also provided having top and bottom ends and being invertible between top-up and bottom-up positions. Gas vent-liquid fill rigid conduit means are vertically aligned with a first end terminating in the top end of the container (b) and a second end outside and above the container (b) top end. Second coupling means are joined to and axially aligned above the rigid conduit means second end. The first and second coupling means are arranged and constructed for axial alignment and rigid vertical joining. Liquid withdrawal-gas vent conduit means are provided with a first end terminating in the bottom end of container (b). A second end of such conduit means extends outside and above the top end of this container. The apparatus also includes an invertible liquid vaporizing-gas vent control circuit comprising liquid sensing means joined to the liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joined at one end to the liquid sensing means, atmospheric gas vent valve means joining the other end of the atmospheric vaporizer, and signal transmitting means for automatically closing said atmospheric gas vent valve means in response to the sensing of liquid by the liquid sensing means. User gas supply valve means are located between the atmospheric vaporizer other end and the vent valve means.

An important characteristic and improvement of this cryogenic liquid storage-gas supply system is the dual function of certain elements. For example, the conduit means used for gas venting of the storage-dispensing container highest zone (top-up end) to avoid overpressure during the gas supply step becomes the liquid fill conduit means when the container is inverted to the bottom-up position. Cryogenic liquid is upwardly charged from the supply container through this same conduit into the lowest zone (top-down end) of the inverted storage-dispensing container. Also, the conduit used for liquid withdrawal from the lowest zone (bottom-down end) of the storage-dispensing container during the liquid charging step. The atmospheric vaporizer used for vaporizing liquid discharged from the storage-dispensing container during the gas supply step is used to warm the cold vent gas during the liquid charging step, thereby avoiding the discharge of cold gas in the close vicinity of the user. This interchangability of function facilitates an extremely light and compact system well-suited for supplying breathing oxygen to people who must move about while carrying the storage-dispensing container. It also permits complete filling of the storage-dispensing container with cryogenic liquid.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic drawing in cross-sectional elevation of a cryogenic liquid storage-dispensing container and liquid vaporizing-gas vent control circuit in the top-up position, during the gas supplying step.

FIG. 2 is a schematic drawing in cross-sectional elevation of the FIG. 1 container-control circuit in the inverted bottom-up position and joined to a cryogenic liquid supply container, during the liquid charging and gas vent step. 7

FIG. 3 is a schematic drawing in cross-sectional elevation of a preferred liquid vaporizing-gas vent control circuit in the top-up position, and differing from the FIG. 1 embodiment by the employment of pneumatic control and a four-way atmospheric gas vent valve means.

FIG. 4 is a cross-sectional view of a quick-opening plug valve suitable for use as the cryogenic liquid supply container and liquid storage-dispensing container fluid connection means, and

7 FIG. 5 is a graph showing the pressure-time relationship for charging the FIG. 3 storage-dispensing container with liquid oxygen in the FIG. 2 manner and from a supply container at several pressure levels.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specifically to the drawings, FIG. 1 illustrates a vertical cryogenic liquid storagedispensing container 10 during the gas supplying period. Container 10 comprises an outer casing 11 and an inner vessel 12 for holding the cryogenic liquid, with an evacuable space therebetween preferably filled with thermal insulation 13 as for example the alternate layers of aluminum foil and glass fiber sheets described in U.S. Pat. No. 3,007,596 to L. C. Matsch. Container 10 has top and bottom ends 14 and 15, respectively, and is invertible between top-up and bottom-up positions. It is preferably sufficiently small for manual movement and inverting. Gas vent-liquid fill rigid conduit means 16 is vertically aligned with a first end 17 extending through and terminating in the normally top-up end 14 of container 10 and a second end 18 outside and above such normally top-up end. Second coupling means 19 (discussed hereinafter in detail) is joined to and above second end 18 when container 10 is in the top-up position. Safety release valve 20 communicates with the container normally top-up end 14 and may for example be joined to conduit means 16 outside container 10 intermediate first and second ends 17 and 18.

Liquid withdrawal-gas vent conduit means 21 also extends through the container top end 14 and the first end 22 thereof terminating in the normally bottomdown end 15 above the inner vessel base. The second end 23 of liquid withdrawal-gas vent means 21 is outside and above the normally top-up end 14 of container 10. invertible liquid vaporizing-gas vent control circuit 24 comprises liquid sensing means 25 joined to the liquid withdrawal-gas vent means second end 23, an atmospheric vaporizer 26 joined at one end to the liquid sensing means 25, and atmospheric gas vent means 27 joining the other end of the atmospheric vaporizer.

Signal transmitting means are also provided for automatically closing atmospheric gas vent valve means 27 in response to the sensing of liquid by the liquid sensing means. Such means may for example be based on a thermistor 25a and comprise electric signal receiving wire 28, controller 29, and electric signal transmitting wire 30 joined to a solenoid-operated vent gas valve 27. More particularly, controller 29 contains a relay and low amperage current flows from the relay coil through wire 28 and thermistor 28. With only gas flow around thermistor 28 its resistance is 100-300 ohms but when wet with cyrogenic liquid its resistance increases to 6,000-10,000 ohms. This increased resistance trips the controller 29 relay so that its contacts open in the wire 30 circuit to vent valve 27, closing same.

During the gas supplying period, the user may select gas (e.g.) oxygen) supplying rates by manually controlling supply valve 31 located between the atmospheric vaporizer other end (opposite liquid sensing means 25) and gas vent valve 27. When valve 31 is open, overhead vapor pressure forces cryogenic liquid upwardly from the container lowest zone or end and through liquid withdrawal-gas vent conduit 21, past liquid sensing,

cryogeqic liquid, with an evacuable space therebetween preferably filled with thermal insulation 43. Cryogenic liquid may be introduced to supply container through feed valve 44 and inlet conduit 45, also provided with safety relief valve 46. This liquid is preferably prewarmed prior to introduction such that it is saturated at the operating pressure desired for discharging same into container 10 as for example described in US. Pat. No. 2,95l,348 to Loveday et al. For example, if the desired oxygen vapor pressure is 40 psig, saturated liquid oxygen at 168C (105K) may be introduced to a supply container of 17.5 liters liquid capacity and provided with 0.4 inch of aluminum foil-glass paper alternate layer insulation of 0.040 X 10 Btu/hr. X ft? F/ft. thermal conductivity in the evacuated space at a density of about 60 foils/inch. Alternatively, subcooled liquid oxygen may be introduced to the sams supply container and upon mild, occasional agitation of the supply container, sufficient saturated pressure canbe eventually obtainer to operate the system. If such pressure is substantially lower than 40 psig than an appropriate revision must be made in the set point of the liquid sensor when the pneumetic system of FIG. 3 is employed (discussed hereinafter in detail).

As an alternative for insuring that the vapor pressure in container 41 is sufficient to discharge the cryogenic fluid into container 10 at the desired temperature and pressure, means may be provided for controllably introducing external heat to container 41 More particularly when and if the vapor pressure drops below a predetermined level, liquid may be controllably withdrawn through conduit by opening valve 51 therein, vaporized in atmospheric vaporizer 52 and returned as vapor to the top end of inner vessel 42. It should be understood that the aforedescribed pressure building circuit 50-52 is not required if the cryogenic liquid is introduced to container 40 in the prewarmed saturated container.

For charging of container 10, the latter is inverted and positioned in vertical alignment with and above supply container 40. Supply container 40 is provided with liquid discharge rigid conduit 53 which is vertically aligned with first end 54 terminating in the bottom end of inner vessel 42 and second end 55 outside and above the container top end. First coupling means 56 are joined to and axially aligned above the conduit second end 55. First and second coupling means 56 and 19 respectively are arranged and constructed for axial alignment and rigid vertical joining, preferably in a manner such that fluid communication is established on joining.

Cryogenic liquid flows upwardly through conduit 53, second coupling means 56, first coupling means 19, and vapor vent-liquid fill conduit means 16, and emerges from the latters first end 17 into the lowest zone of inverted container 10 which is its normally top end 14. The conduit 16 previously used for vapor venting during the liquid storagedispensing and gas supply step is now used for liquid filling.

As liquid transfer progresses, cryogenic vapor in the highest zone of inverted container 10 which is its normally bottom end 15, must be vented in order that the pressure in 15 will be lower than that in container 41 by an amount greater than the hydrostatic head to be overcome. To insure that such pressure differential exists, vapor from container 10 is admitted to the first end 22 of liquid withdrawal-gas vent conduit 21 for. flow through inverted circuit 24 past liquid sensing means 25, further warming in atmospheric vaporizer 26 and release through opened atmospheric gas vent valve means 27. Accordingly, during the liquid charging step the invertible circuit 24 previously used forliquid discharge and vaporization during the gas supply step is now used for gas venting.-

The cryogenic fluid discharged from inverted container 10 during the liquid charging step is sensed by element 25a. When container 10 is full of liquid, the latter will start to flow into the inverted liquid vaporizing-gas vent control circuit 24. Element 25a detectsthe presence of liquid prior to its reaching atmospheric vaporizer 26, and the detection is used as a signal to automatically close gas vent valve means 27, i.e. through electric signal receiving wire 28, controller 29, and electric signal transmitting wire 30; Once valve means 27 is closed the pressure differential between containers l0 and 40 will drop to a value substantially equal to the hydrostatic head produced. by the difference be tween the liquid-gas interfaces in the two containers. When this occurs liquid transfer ceases. First and second coupling means 56 and 19 respectively are now disconnected, container 10 is returned to its normally top-up position and the previously described gas supply step is reinstated. First and second coupling means 56 and 19 are preferably of the type that automatically close when disconnected so that shut-off valves are not needed in gas vent-liquid fill conduit means 16 and liquid discharge conduit 53.

One advantage of the liquid charging termination control system of this invention is the prevention of inadvertent cryogenic liquid dispensing from container 10. If the latter is in its normally top-up position and if the charging sequence is inadvertently initiated by manually opening gas vent valve 27, liquid will immediately appear at the location of sensor 25a. The liquid charging, termination control system quickly automatically re-closes the vent valve.

FIG. 3 illustrates another and preferred liquid charging termination control system based on the generation of a pressure rise on liquid sensing in circuit 24, and pneumatic rather than electric signal transmission to gas vent valve 27. The cryogenic liquid storage dispensing container 10, gas vent-liquid fill conduit means 16, and liquid withdrawal-gas vent conduit means 21 are substantially identical to FIG. 1 and operate in the previously described manner.

The FIG. 3 liquid vaporizing-gas vent control circuit 24 includes smaller size control fluid conduit 60 joined at one end as liquid sensing means 25 to the second end 23 of liquid withdrawal-gas vent conduit 21 outside and above the normally top end 14 of container upstream of primary atmospheric vaporizer 26. A smaller secondary atmospheric vaporizer 62 is provided in control fluid conduit 60 and a first flow restrictor as for example orifice 63 is positioned between the one end 25 of conduit 60 and secondary atmospheric vaporizer 62. Second flow restrictor 64 is located between secondary atmospheric vaporizer 62 and the other end 65 of fluid control conduit 60. Such other end 65 is joined to atmospheric gas vent valve 27, preferably the illustrated four-way type. With such a valve, during the cryogenic liquid charging of container 10 gas may be simultaneously vented through a major vent gas circuit and a minor vent gas circuit. When the liquid charging is completed, the four-way valve 27 closes the two separate vent gas circuits from communication with the atmosphere by interconnected same. More particularly, a first flow passage is established through the valve connecting first inlet port 27a and first outlet port 27b, and

permits venting of a major portion of the vent gas through primary atmospheric vaporizer 26. A second flow passage is also established connecting second inlet port 270 and second outlet port 27d, and permits venting of a minor vent gas portion through control fluid conduit 60. To terminate the liquid charging, the flow passages are realigned as that first and second inlet ports 27a and 27c are connected. A small diameter pressure transmitting conduit 66 has one end joining control fluid conduit 60 between flow restrictors 63 and 64 and preferably between secondary atmospheric vaporizer 62 and second flow restrictor 64, and the other end joined to pneumatic actuator 67 mechanically coupled to four-way atmospheric gas vent valve 27. First flow restrictor 63 and second flow restrictor 64 are sized so that a pneumatic signal is transmitted through conduit 66 to close valve 27 when the pressure in control fluid conduit 60 intermediate secondary atmospheric vaporizer 62 and second flow restrictor 64 rises to a predetermined level.

When the FIG.,-3 container 10 and liquid vaporizinggas vent control circuit 24 are in the inverted bottomup position and connected to cryogenic liquid supply container 40 in a manner analogous to FIG. 2, four-way valve 27 is manually set to the open position. The vent gases flow from inverted container 10 through both the major and minor vent gas circuits to the atmosphere. During this cryogenic liquid charging step, the resistance to fluid flow in the minor vent gas circuit is much greater than that in the major circuit due to first and second flow restrictors 63 and 64. Accordingly, most of the venting gas flows through primary vaporizer 26. During the succeeding gas supplying step, virtually all of the cryogenic liquid discharged from top-up container 10 flows to primary vaporizer 26 (due to lower flow resistance).

When the inverted FIG. 3 container 10 is filled with cryogenic liquid, the latter begins to exit through both the major and minor vent circuits. Again, most of the liquid flows to the major circuit including primary vaporizer 26, is vaporized and released to the atmosphere as a warm gas. Some of the overflowing liquid is carried into the control fluid conduit 60. Compared to the previously flowing cold gas, first flow restrictors 63 passes relatively more mass of fluid as liquid with a much reduced previous drop, and supplies this liquid to the secondary atmospheric vaporizer 62. The liquid is vaporized and warmed rapidly therein and increases several hundred fold in volume. Suddenly, a much larger volume of gas flows to the second flow restrictor 64 which now becomes the limiting resistance in conduit 60. The pressure in this conduit between the first and second flow restrictors 63 and 64 will rise abruptly to balance the new flow of inlet liquid (instead of inlet gas). This pressure rise is transmitted by conduit 66 to pneumatic actuator 67 which operates to set four-way gas vent valve 27 to the closed position. When this occurs, the pressure levels throughout the supply and storagedispensing containers 10 and 40 and the interconnected fluid conduits will equalize (except for the aforementioned hydrostatic head) and liquid charging is stopped.

The elements of the liquid vaporizing-gas vent control circuit 24 are sized and selected so that the necessary pressure level to actuate the pneumatic system for closing gas vent valve 27 is readily and dependably obtained well within the limitations of acceptable pressures for containers l0 and 40. Further, the circuit elements are preferably sized so that liquid sensing response is sufficiently fast to prevent cryogenic liquid spillage from vent valve 27. For example, the first flow restrictor 63 is preferably sized so that when cryogenic liquid reaches the liquid vaporizing gas vent control circuit 24 at the end ofliquid charging, only a small quantity of liquid passes through the restrictor and it does not exceed the capacity of secondary vaporizer 62. The second flow restrictor 64 downstream vaporizer 62 is sized to provide sufficient flow resistance to the nowvaporized liquid so that the gas pressure level sharply rises to the desired level between the two flow restrictors thereby generating a reliable signal.

FIG. 4 illustrates a commercially available quickopening plug valve assembly in the disconnected mode, suitable for use as the first and second coupling means 56 and 19, the function of which was described in connection with FIG. 2. Each part contains a spring loaded plug valve which engage upon coupling and are retracted from their seats by the coupling action to obtain flow communication through the assembly. First means 56 containplug 70 which seals by means of O-ring 71 against the opening in the small end of body 72. Plug 70 is urged against the seat 73 by spring 74 and the plug is guided in its movement by sleeve 75 which is attached inside body 72. The large ring portion 76 of sleeve 75 is shown in section in this view, but is actually a spider construction which permits flow communication upstream and downstream of its attachment to the body 72.

Second coupling means 19 contain a plug valve assembly very similar to that of first coupling means 56. Corresponding parts are: 70 80, 71 81, 72 82, 73 83, 74 84, 75 85, 76 86. When means 19 and 56 are connected, first coupling means 56 fits inside the enlarged recess of second coupling means 19 and ball bearings 87 engage and interfit groove 88 thereby locking the two parts together. Sleeve 89 is retractable against spring 90, thereby permitting ball bearings 87 to expand sufficiently to snap into groove 88. After the balls are recessed into groove 88, sleeve 89 is released and returned to its position over balls 87 thereby preventing inadvertent disengagement of the coupling.

One embodiment of the invention is designed as a portable oxygen gas supply for breathing purposes. The liquid oxygen supply container 41 comprises a nominal 0.025 inch thick stainless steel cylindrical inner vessel of 1 l inch inside diameter and 14.18 inch length, having 17.5 liters liquid capacity. The external cylindrical casing is formed of nominal 0.08 inch thick aluminum with'l3.3 inch outside diameter and 20.75 inch length. The intervening evacuated space is provided with sufficient aluminum foil glass paper alternate layered thermal insulation to reduce the heat inleak such that container normal evaporation rate is 1.4 lbs. oxygen per day. The liquid discharge conduit 53 is a 0.25 inch outside diameter 0.010 inch thick stainless steel tube, and coupling means 56 similar to FIG. 4 is provided on the outer end of this conduit. A safety relief device 46 set at 56 psig. permits storage of substantially liquid oxygen at vapor pressure of about 40 psig.

The liquid oxygen storage-dispensing containercomprises a nominal 0.025 inch thick stainless steel cylindrical inner vessel of 4 inch inside diameter and 8.25 inch height. having 1.3 liters capacity. The external cylindrical casing is formed of nominal 0.025 inch thick stainless steel, with 4.75 inch inside diameter and 9.88 inch length. The evacuated intervening space is filled with sufficient aluminum foil-glass paper alternate lay ered thermal insulation to reduce the heat inleak such that the container normal evaporation rate is 0.6 lbs. oxygen per day. The gas vent-liquid fill conduit 16 is 0.125 inch outside diameter X 0.006 inch thick stainless steel tubing and the liquid withdrawal-gas vent conduit 21 is 0.188 inch outside diameter X 0.010 inch thick stainless steel tubing. Coupling means 19 is similar to FIG. 4. Safety relief valve 20 is set at 52 psig.

The liquid vaporizing-gas vent circuit 24 is as illustrated in H0. 3, and is formed by 0.25 inch outside diameter X 0.032 inch thick aluminum tubing. Primary atmospheric vaporizer 26 comprises seventeen turns of 0.25 inch outside diameter X 0.032 inch thick aluminum tubing formed in a coil of about 4 inches diameter. The four-way pneumatically operated vent valve 27 (sold by Humphrey Products Co., PO. Box 2008, Kalamazoo, Mich. as Model 4PP modified for oxygen service) is sized to produce 40 psi. pressure drop when flowing 3.3 cubic feet per minute (NTP) oxygen through one inlet port and one outlet port only. Control fluid conduit 60 includes secondary atmospheric vaporizer 62 comprising 5.1 square inches of surface area in the form of 6.5 linear inches of the aforementioned tubing. First and second orifices 63 and 64 are 0.016 inch and 0.026 inch diameter respectively. They are sized to product pressure of less than 10 psig. therebetween with only vapor flowing the vent circuits. However, .with the appearance of liquid oxygen in the vent I circuits the pressure between the two orifices rises to a level greater than 30 psig. and pneumatic pressure through conduit 66 is received by actuator 67 set at 28:3 psig. to close vent valve 27. Theuser gas supply valve 31 is a multiple flow selector type permitting withdrawal rates of 1, 2, 4, 6 and 7 liters per minute (NTP).

The aforedescribed oxygen breathing system was also used for a series of experimental liquid oxygen chargings from a liquid oxygen supply container 41 at vapor pressures of 40, 50 and 58 psig. and with saturated liquid oxygen at temperatures of about 107 and 109K. respectively. For each test,the storage and dispensing container 10 had been essentially emptied of its liquid contents but was still cold from the previous liquid charge. The residual oxygen vapor in container 10 was at a nominal pressure of 20 psig. prior to start of the liquid oxygen charging. The FIG. 5 graph shows the results of these tests, i.e. the pressure history at the juncture point between pressure transmitting conduit 66 and control fluid conduit 60 as a function of time. As would be expected, higher supply container pressures resulted in quicker charges. All three charges were terminated when the entrance of liquid into the liquid vaporizing-gas vent control circuit 24 caused the pressure to increase to about 30 psig. When the fourway atmospheric vent valve was closed, the entire system pressure-equalized at the storage container pressure. For all three tests, the quantity of liquid oxygen transferred into the storage and dispensing container 10 (about 3.2 lbs. 0 and the quantity of vent gas loss (about 0.5 lbs. 0 was approximately the same. These experiments demonstrate the effectiveness of the system in charging a relatively large quantity of liquid oxygen from a supply container to a stoarge and dispensing container in an exceedingly short time with only moderate loss of vent gas.

Although certain embodiments have-been described in detail, it will be appreciated that other embodiments are contemplated and that modifications of the disclosed features are within the scope of the invention. For example, the major and minor vent gas circuits of P16. 3 might be connected upstream of a two-way gasvent valve 17 instead of the illustrated four-way valve. However, the latter is preferred because the provision of a separate flow passage through the valve for the control circuit results in low pressure drop in the control fluid across the valve. Thus, most of the pressure drop available at the control circuit will exist across the two restrictors and a larger more positive pneumatic signal can be generated. If only one valve were used in the vent gas circuit, its pressure drop would be high and the total residual pressure drop across the restrictors 63, 63 would be only that across primary vaporizer 26. Unless the single vent valve was sized quite large, (so as to be relatively bulky and expensive), the result would be thatonly a relatively small fraction of the available total pressure drop for venting gas during the cryogenic liquid charging step (supply container pressure to atmospheric pressure) would be available in the pneumatic signal transmitting conduit. This means that a two-way vent valve reduces the responsiveness of the control system and increases the time required to close the vent valve and terminate cryogenic liquid charging of container 10, thereby increasing the vent gas loss.

In the event that subcooled liquid is fed to supply container 41 and the needed vapor pressure for liquid discharge to inverted storage-dispensing container is provided by vaporization in pressure building circuit 50-52 of FIG. 2, means must also be provided for saturating the cryogenic liquid prior to entering or inside container 10. This may be accomplishedby providing a very short uninsulated or poorly insulated section in liquid discharge conduit 53 outside and above supply container 41 but beneath second end 55. The liquid would then be charged into container 10 in the saturated condition, ready for dispensing through liquid withdrawal-gas vent conduit 21 when the container is turned to its top-up position. Alternatively, a separate pressure building circuit identical to circuit 50-52 could be provided in container 10 to generate the needed vapor pressure in situ. For an oxygen therapy system this modification is less desirable than a saturator section in conduit 53 of supply container 41, because of the added weight and complexity to manually invertible container 10.

What is claimed is:

l. A cryogenic liquid storage-gas supply system comprising:

a. a thermally insulated cryogenic liquid supply container having top and bottom ends, liquid discharge rigid conduit means being vertically aligned with a first end terminating in the bottom end of said supply container and a second end outside and above the top end of said supply container, and first coupling means joined to and axially aligned above said liquid discharge conduit second end;

b. a thermally insulated cryogenic liquid storagedispensing container having top and bottom ends and being invertible between top-up and bottomup positions;

0. gas vent-liquid fill rigid conduit means being vertically aligned with a first end terminating in the top end of container (b) and a second end outside and above the top end of container (b), and second coupling means joined to and axially aligned above the rigid conduit means second end, with said first and second coupling means being arranged and constructed for releasable axial alignment and-rigid vertical joining;

d. liquid withdrawal-gas vent conduit means with a first end terminating in the bottom end of container (b) and a second end outside and above the top end of container (b);

e. an invertible liquid vaporizing-gas vent control circuit outside container (b) comprising liquid sensing means joined to said liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joined at one end to saidliquid sensing means, atmospheric vaporizer joined at one end to said liquid sensing means, atmospheric gas vent valve means joining the other end of said atmospheric vaporizer, and signal transmitting means-for automatically closing said atmospheric gas vent valve means in response to the sensing of liquid by said liquid sensing means; and

f. user gas supply valve means between said atmospheric vaporizer other end and said vent valve means.

2. A cryogenic liquid storage-gas supply system according to claim 1 wherein invertible liquid vaporizinggas vent control circuit (e) comprises a primary atmospheric vaporizer joined at one end to said liquid withdrawal-gas vent conduit means second end; pneumatically operated four-way atmospheric gas vent valve means joining the other end of said primary atmospheric vaporizer in a manner such that warmed gas from said primary atmospheric vaporizer flows through a first inlet opening and a first outlet opening of said vent valve means to the atmosphere during cryogenic liquid fill of container (b); a control fiuid conduit also joined at one end to said liquid withdrawal-gas vent conduit means second end comprising a secondary atmospheric vaporizer, a first flow restrictor between said control fluid conduit one end and said secondary atmospheric vaporizer, a second flow restrictor between said secondary atmospheric vaporizer and the other end of said control fluid conduit which other end is joined to said vent valve means in a manner such that warmed gas from said secondary atmospheric vaporizer flows through a second inlet opening and a second outlet opening of said vent valve means to the atmosphere during cryogenic liquid fill of container (b); a pressure transmitting conduit having one end joined to said control fluid contact between said first flow restrictor and said second flow restrictor, and the other end joined in operative relation to said vent valve means, said first and second flow restrictors being sized so that a pneumatic signal is transmitted through said pressure transmitting conduit to close said valve means when the pressure intermediate said first and second flow restrictors rises to a predetermined level; and user gas supply valve means (f) is between said primary atmospheric vaporizer other end and said vent valve means.

3. A cryogenic liquid storage-gas supply system according to claim 1 wherein invertible liquid vaporizinggas vent control circuit (e) comprising a primary atmospheric vaporizer joined at one end to said liquid withdrawal-gas vent conduit means second end; pneumatically operated atmospheric gas vent valve means joining the other end of said primary atmospheric vaporizer; a control fluid conduit also joined at one end to said liquid withdrawal-gas vent conduit means second restrictor, comprising a secondary atmospheric vaporizer, a first flow restrictor between said control fluid conduit one end and said secondary atmospheric vaporizer, a second flow restrictor between said secondary atmospheric vaporizer and the other end of said control fluid conduit which other end is joined to said vent valve means; a pressure transmitting conduit having one end joined to said control fluid conduit between said first flow restrictor and said second flow resistor, and the other end joined in operative relation to said vent valve means, said first and second flow restrictors being sized so that a pneumatic signal is transmitted through said pressure transmitting conduit to close said valve means when the pressure intermediate said first and second flow restrictors rises to a predetermined level; and user gas supply valve means (f) is between said primary atmosphere vaporizer other end and said vent valve means.

4. A cryogenic liquid storage-gas supply system according to claim 1 wherein a pressure building circuit is joined to container (a) comprising second liquid discharge conduit means with a first end terminating in the bottom end of the container, an intermediate section outside said container and a second end terminating in the top end of said container, and atmospheric vaporizer and control valve means in said intermediate section.

5. A cryogenic liquid storage-gas supply system according to claim 4 wherein said liquid discharge rigid conduit means of container (a) includes a short uninsulated saturator section outside the container top end.

6. A method for supplying gas from a cryogenic liquid supply container and a storage-dispensing container comprising the steps of:

a. providing a thermally insulated cryogenic liquid supply container;

b. providing a thermally insulated cryogenic liquid storage-dispensing container having top and bottom ends and being invertible between top-up and bottomup positions;

c. inverting and positioning container (b) in vertical alignment with and above container (a), and joining the container (b) bottom and container (a) top in cryogenic liquid flow communication;

d. charging container (b) with cryogenic liquid from container (a) by flowing such liquid upwardly from the lowest zone of container (a) by vapor pressure of liquid therein, to the lowest zone of container e. continuing the cryogenic liquid flowing of (d), and discharging cryogenic vapor from the highest zone of inverted container (b) through the normally top end thereof for warming by and venting to the atmosphere;

f. sensing the cryogenic fluid discharged from inverted container (b) during the cryogenic liquid charging and vapor discharging of (cl) and (e) and terminating the cryogenic liquid charging and vapor discharging in response to sensing of liquid;

g. disconnecting containers (a) and (b) and turning cryogenic liquid-filled container (b) to its top-up position;

h. flowing cryogenic liquid by overhead vapor pressure upwardly from the lowest zone of container (b), discharging such liquid from the container top end, vaporizing the so-discharged liquid by atmospheric heat to form a gas supply; and

i. continuing the liquid discharging and vaporization of (h) until container (b) is depleted of liquid, and thereafter repeating steps (c) through (h).

7. A method according to claim 6 wherein the cryogenic liquid is discharged in the saturated condition from container (a) during the container (b) charging step (d).

8. A method according to claim 6 wherein the cryogenic liquid is discharged in the subcooled condition from container (a) and saturated by atmospheric heat prior to charging into container (b) during step (d).

9. A method for supplying gas from a cryogenic liquid supply container and a storage-dispensing container comprising the steps of:

a. providing a thermally insulated cryogenic liquid supply container having top and bottom ends, liquid discharge rigid conduit means being vertically aligned with a first end terminating in the bottom end of said supply container and a second end outside and above the top end of said supply container and first coupling means joined to and axially aligned above the liquid discharge conduit second end;

b. providing a thermally insulated cryogenic liquid storage-dispensing container with top and bottom ends and being invertible between top-up and bottom-up positions, having vertically aligned gas vent liquid fill rigid conduit means with a first end terminating in the top end of said container and second coupling means joined to the second end outside and above said container, with saidfirst and second coupling means being arranged and constructed for axial alignment and rigid vertical joining, liquid withdrawal-gas vent conduit means with a first end extending through and terminating in the bottom end of said container and a second end outside and above the top end of said container;

c. providing an invertible liquid vaporizing-gas vent control circuit comprising liquid sensing means joined to said liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joined at one end to said liquid sensing means, atmospheric gas vent valve means joining the atmospheric vaporizer other end, and signal transmitting means for automatically closing said vent valve means in response to the sensing of liquid by said liquid sensing means, and user gas supply valve means between said atmospheric vaporizerother end and said vent valve means;

(1. inverting container (b) and liquid vaporizing-gas vent control circuit (a), and positioning container (b) in vertical alignment with. and above container (a), and joining said first and second coupling means; i

e. charging container (b) with cryogenic liquid from container (a) by opening said vent valve means for flowing cryogenic liquid upwardly from the lowest zone of container (a) by overhead vapor pressure through said liquid discharge rigid conduit means and said gas vent-liquid fill rigid conduit means to the lowest zone of container (b);

f. continuing the cryogenic liquid charging of (e) and discharging cryogenic vapor from the highest zone of inverted container (b) sequentially through said liquid withdrawal-gas vent conduit means, said cryogenic fluid sensing means, said atmospheric vaporizer and said vent valve means;

g. sensing the cryogenic fluid temperature by said sensing means during the liquid charging and vapor discharging of (e) and (f), and terminating the cryogenic liquid charging and vapor discharging when cryogenic liquid is sensed, by closing said vent valve means;

h. disconnecting said first and second coupling means and turning cryogenic liquid-filled container (b) and liquid vaporizing-gas vent control circuit (c) to their top-up gas supplying position;

. opening said gas supply valve .means and discharging gas thereto being derived from cryogenic liquid flowing upwardly by overhead vapor pressure from the lowest zone of container (b) through said liquid withdrawal-gas vent conduit means, and vaporized in said atmospheric vaporizer;

j. continuing the liquid discharging and vaporization of (i) until container (b) is depleted of liquid, and thereafter consecutively repeating steps (d) through (i). 

1. A cryogenic liquid storage-gas supply system comprising: a. a thermally insulated cryogenic liquid supply container having top and bottom ends, liquid discharge rigid conduit means being vertically aligned with a first end terminating in the bottom end of said supply container and a second end outside and above the top end of said supply container, and first coupling means joined to and axially aligned above said liquid discharge conduit second end; b. a thermally insulated cryogenic liquid storage-dispensing container having top and bottom ends and being invertible between top-up and bottom-up positions; c. gas vent-liquid fill rigid conduit means being vertically aligned with a first end terminating in the top end of container (b) and a second end outside and above the top end of container (b), and second coupling means joined to and axially aligned above the rigid conduit means second end, with said first and second coupling means being arranged and constructed for releasable axial alignment and rigid vertical joining; d. liquid withdrawal-gas vent conduit means with a first end terminating in the bottom end of container (b) and a second end outside and above the top end of container (b); e. an invertible liquid vaporizing-gas vent control circuit outside container (b) comprising liquid sensing means joined to said liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joined at one end to said liquid sensing means, atmospheric vaporizer joined at one end to said liquid sensing means, atmospheric gas vent valve means joining the other end of said atmospheric vaporizer, and signal transmitting means for automatically closing said atmospheric gas vent valve means in response to the sensing of liquid by said liquid sensing means; and f. user gas supply valve means between said atmospheric vaporizer other end and said vent valve means.
 2. A cryogenic liquid storage-gas supply system according to claim 1 wherein invertible liquid vaporizing-gas vent control circuit (e) comprises a primary atmospheric vaporizer joined at one end to said liquid withdrawal-gas vent conduit means second end; pneumatically operated four-way atmospheric gas vent valve means joining the other end of said primary atmospheric vaporizer in a manner such that warmed gas from said primary atmospheric vaporizer flows through a first inlet opening and a first outlet opening of said vent valve means to the atmosphere during cryogenic liquid fill of container (b); a control fluid conduit also joined at one end to said liquid withdrawal-gas vent conduit means second end comprising a secondary atmospheric vaporizer, a first flow restrictor between said control fluid conduit one end and said secondary atmospheric vaporizer, a second flow restrictor between said secondary atmospheric vaporizer and the other end of said control fluid conduit which other end is joined to said vent valve means in a manner such that warmed gas from said secondary atmospheric vaporizer flows through a second inlet opening and a second outlet opening of said vent valve means to the atmosphere during cryogenic liquid fill of container (b); a pressure transmitting conduit having one end joined to said control fluid contact between said first flow restrictor and said second flow restrictor, and the other end joined in operative relation to said vent valve means, said first and second flow restrictors being sized so that a pneumatic signal is transmitted through said pressure transmitting conduit to close said valve means when the pressure intermediate said first and second flow restrictors rises to a predetermined level; and user gas supply valve means (f) is between said primary atmospheric vaporizer other end and said vent valve means.
 3. A cryogenic liquid storage-gas supply system according to claim 1 wherein invertible liquid vaporizing-gas vent control circuit (e) comprising a primary atmospheric vaporizer joined at one end to said liquid withdrawal-gas vent conduit means second end; pneumatically operated atmospheric gas vent valve means joining the other end of said primary atmospheric vaporizer; a control fluid conduit also joined at one end to said liquid withdrawal-gas vent conduit means second restrictor, comprising a secondary atmospheric vaporizer, a first flow restrictor between said control fluid conduit one end and said secondary atmospheric vaporizer, a second flow restrictor between said secondary atmospheric vaporizer and the other end of said control fluid conduit which other end is joined to said vent valve means; a pressure transmitting conduit having one end joined to said control fluid conduit between said first flow restrictor and said second flow resistor, and the other end joined in operative relation to said vent valve means, said first and second flow restrictors being sized so that a pneumatic signal is transmitted through said pressure transmitting conduit to close said valve means when the pressure intermediate said first and second flow restrictors rises to a predetermined level; and user gas supply valve means (f) is between said primary atmosphere vaporizer other end and said vent valve means.
 4. A cryogenic liquid storage-gas supply system according to claim 1 wherein a pressure building circuit is joined to container (a) comprising second liquid discharge conduit means with a first end terminating in the bottom end of the container, an intermediate section outside said container and a second end terminating in the top end of said container, and atmospheric vaporizer and control valve means in said intermediate section.
 5. A cryogenic liquid storage-gas supply system according to claim 4 wherein said liquid discharge rigid conduit means of container (a) includes a short uninsulated saturator section outside the container top end.
 6. A method for supplying gas from a cryogenic liquid supply container and a storage-dispensing container comprising the steps of: a. providing a thermally insulated cryogenic liquid supply container; b. providing a thermally insulated cryogenic liquid storage-dispensing container having top and bottom ends and being invertible between top-up and bottom-up positions; c. inverting and positioning contaiNer (b) in vertical alignment with and above container (a), and joining the container (b) bottom and container (a) top in cryogenic liquid flow communication; d. charging container (b) with cryogenic liquid from container (a) by flowing such liquid upwardly from the lowest zone of container (a) by vapor pressure of liquid therein, to the lowest zone of container (b); e. continuing the cryogenic liquid flowing of (d), and discharging cryogenic vapor from the highest zone of inverted container (b) through the normally top end thereof for warming by and venting to the atmosphere; f. sensing the cryogenic fluid discharged from inverted container (b) during the cryogenic liquid charging and vapor discharging of (d) and (e) and terminating the cryogenic liquid charging and vapor discharging in response to sensing of liquid; g. disconnecting containers (a) and (b) and turning cryogenic liquid-filled container (b) to its top-up position; h. flowing cryogenic liquid by overhead vapor pressure upwardly from the lowest zone of container (b), discharging such liquid from the container top end, vaporizing the so-discharged liquid by atmospheric heat to form a gas supply; and i. continuing the liquid discharging and vaporization of (h) until container (b) is depleted of liquid, and thereafter repeating steps (c) through (h).
 7. A method according to claim 6 wherein the cryogenic liquid is discharged in the saturated condition from container (a) during the container (b) charging step (d).
 8. A method according to claim 6 wherein the cryogenic liquid is discharged in the subcooled condition from container (a) and saturated by atmospheric heat prior to charging into container (b) during step (d).
 9. A method for supplying gas from a cryogenic liquid supply container and a storage-dispensing container comprising the steps of: a. providing a thermally insulated cryogenic liquid supply container having top and bottom ends, liquid discharge rigid conduit means being vertically aligned with a first end terminating in the bottom end of said supply container and a second end outside and above the top end of said supply container and first coupling means joined to and axially aligned above the liquid discharge conduit second end; b. providing a thermally insulated cryogenic liquid storage-dispensing container with top and bottom ends and being invertible between top-up and bottom-up positions, having vertically aligned gas vent liquid fill rigid conduit means with a first end terminating in the top end of said container and second coupling means joined to the second end outside and above said container, with said first and second coupling means being arranged and constructed for axial alignment and rigid vertical joining, liquid withdrawal-gas vent conduit means with a first end extending through and terminating in the bottom end of said container and a second end outside and above the top end of said container; c. providing an invertible liquid vaporizing-gas vent control circuit comprising liquid sensing means joined to said liquid withdrawal-gas vent conduit means second end, an atmospheric vaporizer joined at one end to said liquid sensing means, atmospheric gas vent valve means joining the atmospheric vaporizer other end, and signal transmitting means for automatically closing said vent valve means in response to the sensing of liquid by said liquid sensing means, and user gas supply valve means between said atmospheric vaporizer other end and said vent valve means; d. inverting container (b) and liquid vaporizing-gas vent control circuit (a), and positioning container (b) in vertical alignment with and above container (a), and joining said first and second coupling means; e. charging container (b) with cryogenic liquid from container (a) by opening said vent valve means for flowing cryogenic liquid upwardly from the lowest zone of container (a) by overhead vapor pressure through said liquid discharge rigid conduit means and said gAs vent-liquid fill rigid conduit means to the lowest zone of container (b); f. continuing the cryogenic liquid charging of (e) and discharging cryogenic vapor from the highest zone of inverted container (b) sequentially through said liquid withdrawal-gas vent conduit means, said cryogenic fluid sensing means, said atmospheric vaporizer and said vent valve means; g. sensing the cryogenic fluid temperature by said sensing means during the liquid charging and vapor discharging of (e) and (f), and terminating the cryogenic liquid charging and vapor discharging when cryogenic liquid is sensed, by closing said vent valve means; h. disconnecting said first and second coupling means and turning cryogenic liquid-filled container (b) and liquid vaporizing-gas vent control circuit (c) to their top-up gas supplying position; i. opening said gas supply valve means and discharging gas thereto being derived from cryogenic liquid flowing upwardly by overhead vapor pressure from the lowest zone of container (b) through said liquid withdrawal-gas vent conduit means, and vaporized in said atmospheric vaporizer; j. continuing the liquid discharging and vaporization of (i) until container (b) is depleted of liquid, and thereafter consecutively repeating steps (d) through (i). 